某焦化厂煤调湿蒸汽回转干燥机管束失效分析

某焦化厂煤调湿蒸汽回转干燥机管束在运行过程中发生开裂。采用化学成分分析、金相显微镜、扫描电子显微镜以及EDS能谱等手段对失效钢管进行取样分析。根据宏观和微观断口形貌、显微组织、钢管的腐蚀坑及力学性能测试结果，确定了钢管失效原因为应力腐蚀开裂。裂纹起源于钢管表面的点蚀坑，应力来自于钢管承受冷热交替时产生的热应力。

Failure analysis of tube bundle of coal moisturecontrol steam rotary dryer in a coking plant

The tube bundle of one rotary dryer with moisture regulating steam in a coking plant was cracked in the process of operation. The failed steel pipe was analyzed by the means of chemical composition, metallographic microscope, scanning electron microscope and energy dispersive spectrum. According to the test results of macro and micro fracture morphology, microstructure, corrosion pit and mechanical property, it was found that the failure reason of steel pipe was stress corrosion cracking. The crack was originated from the pitting corrosion on the surface of steel pipe, and the stress was from the thermal stress generated when the steel pipe was subjected to alternating low and high temperature.